2024 Author: Leah Sherlock | [email protected]. Last modified: 2023-12-17 05:25
What is reverb? A short answer to this question will be given in this article. In its chapters, readers will find information about the devices with which this effect can be obtained, as well as modern software used for this purpose.
Definition
So what is reverb?
In encyclopedic dictionaries you can find various definitions of this phenomenon. Their essence is roughly as follows. Reverberation is a physical process that is considered in psychoacoustics and acoustics. It can be described as the persistence of a sound after it has been played. Reverb is created when a sound, or the electrical signal it causes, bounces off something several times and then decays.
It stops as it is absorbed by various surfaces in its immediate vicinity. Sound-absorbing objects can be people, furniture, and so on. Air also has some absorption capacity. What is reverb can be understood by pressing any piano key. The note is heard for sometime after the person has removed their hands from the instrument. That is, the source of the sound is silent, but its echo is still audible. It fades away gradually. This is the reverb.
The language of mathematics
The characteristics of the reverb effect depend on some external circumstances. Its length or time is usually called the duration of sound stability starting from the moment when the source fell silent. This interval is measured in milliseconds.
Echo and reverb
Reverb is often confused with echo. In fact, the first concept has a broader meaning. It also includes an echo, which can have a value from 50 to 100 milliseconds. The process discussed in this article is not limited to these frameworks. What is reverb? Speaking in the language of numbers, this is an aftersound, the duration of which can be lower than 50 milliseconds.
Where does reverb exist?
She doesn't only appear indoors. Its natural variant can be heard in the forest, mountains, and in any area where there are large or small objects that can reflect sound.
Reverberation naturally occurs when a person speaks, sings or plays an instrument.
Measurement standard
Reverberation time is, as already mentioned, the number of milliseconds during which the sound decays. It is measured from the moment the source is completely attenuated. When you want to determine its exact value, use a method called RT60.
This is short for "reverberation time".
The number "60" indicates the number of decibels by which the volume of the sound should decrease. When this limit is reached, the time measurement ends.
Height dependent
Usually, reverberation time is denoted by a single number, since not individual frequencies are measured, but the sound as a whole. However, these parameters are dependent on each other. So, for greater accuracy, it is necessary to measure the decay time of various frequencies that make up the sound. The upper range is known to have a longer reverb. Low sounds, on the other hand, fade faster. For this reason, it is better to do a "multi-band" metering, paying attention to each frequency separately.
Pioneer
At the end of the 19th century, American scientist Wallace Clement Sabin began work on the study of sound at Harvard University.
He conducted experiments to study the influence of the degree of absorption of various materials on the decay time of the echo. The physicist used an organ as a sound source. A stopwatch served as a measuring device.
The ears of the researcher himself were also of considerable importance, since in some cases he determined the degree of attenuation of a note by ear. Sabin measured the time it took to lower the volume by 60 decibels. In his research he came to the following results. The physicist found that the reverberation time is directly proportional to the size of the room. The more interior space, thethe note lasts longer.
There is an inverse relationship with the surface area of all objects capable of absorbing sound.
Optimal parameters
The ideal proportions of the room in which music is performed depend on the genre of the work. Each style uses a different reverb time.
Halls intended for meetings, conferences, forums, lectures and similar events, where speakers are expected to speak to the public, should not have such a long reverberation. It is known that the excessive duration of the reflected sound reduces the clarity of speech, and therefore can serve as an obstacle to its understanding. If one syllable continues to be heard while the next is pronounced, the phrase will be illegible. In this case, it will be difficult to understand which word was meant: cat, whale or code. On the other hand, if the reverberation time is too short, then the human voice or the sound of a musical instrument will lose some of its timbre. Music performed in a room with such a characteristic is not interesting to listen to. This will negatively affect the volume as well. Due to the abruptness of the sound, the piece will be perceived as too quiet.
The reverb effect is often used in recording studios to give musical compositions the right color. With it, you can achieve a richer and deeper color, or, conversely, reduce the brightness of a particular part so that it does not drown out others.
Based on the above, we can answer the question "whatsuch a reverberation": this is one of the qualities of sound that is a color and affects the perception of it by listeners. However, changing this indicator does not affect the pitch of the notes. The reverberation of a room depends on its size and shape, as well as on the structure of the surface of walls and other objects, not the last role in this is played by building and finishing materials, or rather, their property such as density, which determines the ability to muffle and reflect sound.
Methods for measuring reverb
The first experiments on measuring the reverberation time were carried out using a graphic apparatus with a moving paper tape, on which the sound volume was recorded. As the oscillations decayed, the device drew a curve that was a graph of this process. The sound for such studies needs to be quite loud and jerky. It should calm down instantly. Therefore, a pistol loaded with blank cartridges was usually chosen as a source, or an inflatable balloon, which, when pierced with a needle, burst and produced a characteristic pop.
Another way to measure the length of a reverb is to record the original sound and its echo after a certain amount of time. Based on this data, the length of the reverb is calculated. This method has a certain advantage over the previously described. Sound recording can be made even in the hall before the start of the concert, when all the spectators have already taken their seats.
To do this, you just need to turn on the music and record it twice in this room.
This determination of the reverberation time for a particular hall will be the most accurate, since the value of this indicator can be influenced by the number of spectators who came, and the materials from which the clothes are sewn, and even the humidity of the air on a particular day.
Artificial reverb
Every sound engineer and producer knows how important this sound parameter is to create a quality soundtrack that will be pleasant and interesting to listen to.
Vocal reverb creates a space effect that makes singing more "alive" and "realistic". In the same way, you can achieve the presence of the "echo" effect in the recording.
The importance of giving these characteristics to the sound when recording actors in cinematography cannot be overstated. It is thanks to the sound engineer's excellent command of techniques for creating artificial voice reverberation that the viewer can be transported with the characters of the tape to a mountain cave or to the spacious halls of the royal palace.
Acoustic devices
One of the first methods to give the sound the right reverb was to simultaneously record, produced in close proximity to the source and at a certain distance from it. These two or more phonograms were superimposed on each other in the required proportions (with a certain volume). This method was also used when recording David Bowie's song Heroes.
Electronic devices were also invented to obtain a similareffect. For example, Abbey Road Studios used a reverb (the so-called apparatus for creating artificial overtones and echoes) based on a large vibrating metal plate. Guitar amplifiers still use devices, the main element of which are iron springs. This method of getting reverb was invented by Hammond, the creator of the famous electric organ.
There are many other reverb devices, all of them working according to their original schemes.
Currently, digital effects are widely used, both made in the form of separate devices (pedals) and numerous computer programs.
Some people, on the contrary, are puzzled by the question of how to remove reverb. This may be necessary if, for example, the recording of an institute lecture made on a dictaphone turned out to be illegible. In this case, the Izotope Rx Dereverb program can help. But only those who have the skills to work in any of the sequencer programs (application for professional recording) will be able to use it, since it is a plug-in, that is, it is built into other applications.
